From fc33b6f591fda70fd64ea34806e5516c695cd89b Mon Sep 17 00:00:00 2001
From: Kurtis Melby <kurt@melby.me>
Date: Mon, 4 Dec 2023 23:55:10 -0500
Subject: [PATCH 1/2] feat: Adding a method to get any object in a map by its
 unique ID

---
 packages/tiled/lib/src/tiled_map.dart | 21 +++++++++++
 packages/tiled/test/map_test.dart     | 51 +++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/packages/tiled/lib/src/tiled_map.dart b/packages/tiled/lib/src/tiled_map.dart
index 8b7bb5b..ef6133a 100644
--- a/packages/tiled/lib/src/tiled_map.dart
+++ b/packages/tiled/lib/src/tiled_map.dart
@@ -91,6 +91,9 @@ class TiledMap {
   List<EditorSetting> editorSettings;
   CustomProperties properties;
 
+  // Cache the object by ID when accessed.
+  Map<int, TiledObject>? _cachedObjects;
+
   // only for hexagonal maps:
   int? hexSideLength;
   StaggerAxis? staggerAxis;
@@ -279,6 +282,24 @@ class TiledMap {
     throw ArgumentError('Layer $name not found');
   }
 
+  /// Finds the [TiledObject] in this map with the unique [id].
+  /// Objects have map wide unique IDs which are never reused.
+  /// https://doc.mapeditor.org/en/stable/reference/tmx-map-format/#object
+  ///
+  /// Returns null if not found.
+  TiledObject? objectById(int id) {
+    if (_cachedObjects == null) {
+      _cachedObjects = {};
+      layers.whereType<ObjectGroup>().forEach((objectGroup) {
+        for (final object in objectGroup.objects) {
+          _cachedObjects![object.id] = object;
+        }
+      });
+    }
+
+    return _cachedObjects?[id];
+  }
+
   Tileset tilesetByName(String name) {
     return tilesets.firstWhere(
       (element) => element.name == name,
diff --git a/packages/tiled/test/map_test.dart b/packages/tiled/test/map_test.dart
index 9b1acd3..7f91085 100644
--- a/packages/tiled/test/map_test.dart
+++ b/packages/tiled/test/map_test.dart
@@ -380,4 +380,55 @@ void main() {
       expect(map.tilesetByName('Humans'), equals(tileset));
     });
   });
+
+  group('Map.objectById', () {
+    late TiledMap map;
+    setUp(() {
+      map = TiledMap(
+        width: 2,
+        height: 2,
+        tileWidth: 8,
+        tileHeight: 8,
+        layers: [
+          TileLayer(
+            name: 'tile layer 1',
+            width: 2,
+            height: 2,
+            data: [1, 0, 2, 0],
+          ),
+          ObjectGroup(
+            name: 'object layer 1',
+            objects: [
+              TiledObject(id: 1, name: 'object one'),
+              TiledObject(id: 5, name: 'object five'),
+            ],
+          ),
+        ],
+        tilesets: [
+          Tileset(
+            name: 'TileSet_1',
+            image: const TiledImage(source: 'tileset_1.png'),
+            firstGid: 1,
+            columns: 1,
+            tileCount: 2,
+            tiles: [
+              Tile(localId: 0),
+              Tile(localId: 1),
+            ],
+          ),
+        ],
+      );
+    });
+
+    test('gets images only in use on each TileLayer', () {
+      final object1 = map.objectById(1);
+      expect(object1?.name, equals('object one'));
+
+      final object5 = map.objectById(5);
+      expect(object5?.name, equals('object five'));
+
+      final object3 = map.objectById(3);
+      expect(object3, equals(null));
+    });
+  });
 }

From 203482beaa5d616caa5de3f078bd42c52c1ed0a1 Mon Sep 17 00:00:00 2001
From: Kurtis Melby <kurt@melby.me>
Date: Tue, 5 Dec 2023 22:45:31 -0500
Subject: [PATCH 2/2] adding comment about caching

---
 packages/tiled/lib/src/tiled_map.dart | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/packages/tiled/lib/src/tiled_map.dart b/packages/tiled/lib/src/tiled_map.dart
index ef6133a..270f425 100644
--- a/packages/tiled/lib/src/tiled_map.dart
+++ b/packages/tiled/lib/src/tiled_map.dart
@@ -286,6 +286,9 @@ class TiledMap {
   /// Objects have map wide unique IDs which are never reused.
   /// https://doc.mapeditor.org/en/stable/reference/tmx-map-format/#object
   ///
+  /// This reads through a cached map of all the objects so it does not
+  /// need to loop through all the object layers each time.
+  ///
   /// Returns null if not found.
   TiledObject? objectById(int id) {
     if (_cachedObjects == null) {